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Normal distribution question

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    Hi everyone, first post.

    I don't understand how I answer this question, despite having done others similar.

    'a student makes the same journey to uni everyday. Lectures start at 9. If he leaves home at 8 he is late 5% of the time. If he leaves home at 7.55 he is late 1% of the time. Assuming the times of his journey are normally distributed with the same mean and std deviation irrespective of starting times, calculate mean and std dev of the journey times.'

    any help would be greatly appreciated
    Thanks
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    Draw the bell curve, plot 8 and 7.55 on it with 0.05 and 0.01 as the respective areas to the left of those point.
    Using the tables and standard formula see what you can do. Ideally it is best if you post some of your working so we can see how far you have got.
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    Can yu tell me if the answer of s.d is 11.25

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Updated: May 5, 2012
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